Stress Tests

Why Are Stress Tests Performed?

Patients with coronary artery blockages may have minimal symptoms and an unremarkable or unchanged EKG while at rest. However, symptoms and signs of heart disease may become revealed by exposing the heart to the stress of exercise. During exercise, healthy coronary arteries widen more than an artery containing a blockage. This uneven dilation causes more blood to be delivered to heart muscle supplied by the normal artery. In contrast, narrowed arteries end up supplying reduced flow to its area of distribution. This reduced flow then causes involved muscle to have inadequate blood supply during exercise. The lack of blood supply may then produce symptoms such as chest discomfort or inappropriate shortness of breath causing the EKG to possibly produce abnormal characteristics. A motorized treadmill is usually used for exercise, while a stationary bicycle is used in some exercise laboratories. Stress tests may be ordered by your provider to determine things such as how well a treatment is working, if you are at high risk for heart disease/complications and even the cause of new chest pain or worsening angina. It can also be used if you are planning to start an exercise program or have surgery. Once completed, the results can help determine how well your heart is pumping, proper treatment for coronary heart disease, determine whether your heart is abnormally large or to diagnose coronary artery disease.

How Are Stress Tests Performed?

This test is done at a medical center or health care provider’s office. It is done in stages:

First, you will have an IV (intravenous line) started. A radioactive substance, such as thallium or sestamibi, will be injected into one of your veins. After that, you will lie down and wait for between 15 and 45 minutes. Later, a special camera will scan your heart and create pictures to show how the substance has traveled through your blood and into your heart. Once an image is obtained, most people will then walk on a treadmill (or pedal on an exercise machine). Once the treadmill starts moving slowly, you will be asked to walk (or pedal) faster and on an incline. If you are not able to exercise, you may be given a medicine called a vasodilator. This drug widens your heart arteries. In other cases, you may get a medicine (dobutamine) that will make your heart beat faster and harder, similar to when you exercise. Throughout the exam, your blood pressure and heart rhythm (ECG) will be monitored.

How to prepare for your stress test?

It is very important to wear comfortable clothes and shoes with non-skid soles. You may be asked not to eat or drink after midnight. You will be allowed to have a few sips of water if you need to take medicines. Keep in mind that many medications can interfere with blood test results. Your provider will tell you if you need to stop taking any medicines before you have this test. Do not stop or change your medicines without consulting your doctor first. You will need to avoid caffeine for 24 hours before the test. This includes Tea, coffee, all sodas (including caffeine-free), chocolates, and certain pain relievers that contain caffeine.

After the test…

A normal test most regularly means that you were able to exercise as long as or longer than most people of your age and gender. You also did not have symptoms or changes in blood pressure, your ECG or the images of your heart that caused concern. A normal result means blood flow through the coronary arteries is probably normal. The meaning of your test results can be subject to the reason for the test, your age, and your history of heart and other medical problems. On the other hand, abnormal results may be due to reduced blood flow to a part of the heart. The most likely cause is a narrowing or blockage of one or more of the arteries that supply your heart muscle and scarring of the heart muscle due to a previous heart attack. After the test, you may require continued treatment such as angioplasty, stent placement, medication changes, or heart bypass surgery.